Answer:
From first law of thermodynamics(energy conservation)
Qa= Qr+W
Qa=Heat added to the engine
Qr=heat rejected from the engine
W=work output from the engine
Second law:
It is impossible to construct a heat engine that will deliver the work with out rejecting heat.
In other word ,if engine take heat then it will reject some amount heat and will deliver some amount of work.
1.
QH=6 kW,
QL=4 kW,
W=2 kW
6 KW= 4 + 2 KW
It satisfy the first law.
Here heat is also rejected from the engine that is why it satisfy second law.
2.
QH=6 kW, QL=0 kW, W=6 kW
This satisfy first law but does not satisfy second law because heat rejection is zero.
3.
QH=6 kW , QL=2 kW, W=5 kW
This does not satisfy first as well as second law.Because summation of heat rejection and work can not be greater than heat addition or we can say that energy is not conserve.
4.
QH=6 kW, QL=6 kW, W=0 kW
This satisfy first law only and does not satisfy second law.
Answer:
A selective surface with large absorption for solar radiation and high reflectance for thermal infrared radiation was produced by use of surface oxidation of stainless steel. The surfaces were studied for use with concentrated light in a solar power plant at temperatures of 400°C and higher.
In order to investigate the relation between surface treatment and optical properties, stainless steels (AISI 304 and 430) which were submitted to different chemical and mechanical surface treatments, were used. To increase the spectral selectivity, these surfaces were treated in air and in vacuum at different temperatures and times. The optical properties of these films were investigated. Visual and infrared spectral absorptances were measured at room temperature. The thermal hemispherical emittance and absorptance were obtained by a calorimetric method at 200°C. It was noticed that these chemically and mechanically treated stainless steel surfaces have good spectral properties without further oxidations. This is very important for high temperature uses. The best values are found for samples 7 and 8 under vacuum and air. These two samples with mechanically ground surfaces retained their selectivity and specularity after several hours oxidation. One can conclude that the surface ground treatment confers good selectivity on the steel surfaces for use in concentrating solar collectors with a working temperature of 500°C.
Sample surfaces were subjected to long temperature ageing tests in order to gain some idea of the thermal stability of the surfaces. The results promise better-performing surface and the production of durable selective finishes at, possibly, lower cost than competing processes.
Explanation:
Answer: Technician A
Explanation: A coolant recovery system Is one of the most important part of a vehicles cooling system. When a coolant gets too hot, it forces it way out of the spring loaded radiator cap so as to relieve pressure. Any coolant which has escaped is recovered back through the discharge tube located in the recovery tank. The system is usually air free
Answer:
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